import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBConfig {
	public static void main(String[] args) {
		DBLink();
	}
	public static void DBLink(){
		String driver = null;
		String url = null;
		String username = null;
		String password = null;
		/**************************************************************
		   *通过读取文件的配置链接数据库
		 **************************************************************/
		File f = new File("config" + File.separator + "config.txt");
		try {
			//如果此目录文件存在就去读
			if (f.exists()) {
				// 读取
				FileReader fr = new FileReader(f);
				BufferedReader fb = new BufferedReader(fr);

				String rDriver = fb.readLine();
				driver = rDriver.substring(7);

				String rUrl = fb.readLine();
				url = rUrl.substring(4);

				String rUserName = fb.readLine();
				username = rUserName.substring(9);

				String rPassword = fb.readLine();
				password = rPassword.substring(9);

/*				System.out.println(driver);
				System.out.println(url);
				System.out.println(username);
				System.out.println(password);*/
				
				/**************************************************************
				   *链接数据库读取数据，并将其写入文件
				 **************************************************************/
				Connection con = null;
				Statement sta = null;
				ResultSet rs = null;
				String sql = "select * from users";
				
				try {
					Class.forName(driver);
					try {
						//链接
						con = DriverManager.getConnection(url, username, password);
						sta = con.createStatement();
						rs = sta.executeQuery(sql);
						File f1 = new File("data" + File.separator + "users.txt");
						f1.createNewFile();
						FileWriter fw = new FileWriter(f1,true);
						String dbStr = null;
						
						while(rs.next()){
							dbStr = "用户ID号：" + rs.getInt("u_id") + "用户名：" + rs.getString("u_name") + "年龄：" + rs.getInt("u_age") + "联系方式：" + rs.getString("u_phone") + "\r\n";
							fw.write(dbStr);
							fw.flush();
						}
						
						System.out.println("数据导出到文件完成！");
					} catch (SQLException e) {
						e.printStackTrace();
					}
				} catch (ClassNotFoundException e) {
					e.printStackTrace();
				}
				
			}else{
				System.out.println("此文件不存在！系统将自动为您创建！");
				//创建文件
				f.createNewFile();
				//写入数据
				FileWriter fw = new FileWriter(f);
				final String wDriver = "driver=oracle.jdbc.driver.OracleDriver\r\n";
				String wUrl = "url=jdbc:oracle:thin:@localhost:1521:ORACLE9I\r\n";
				String wUserName = "username=useinfo\r\n";
				String wPassword = "password=useinfo\r\n";
				fw.write(wDriver);
				fw.write(wUrl);
				fw.write(wUserName);
				fw.write(wPassword);
				fw.flush();
				fw.close();
				System.out.println("创建完成！");
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		
	}	
}